Automatic setting device for shutters and diaphragms of photographic apparatus



Dec. 31, 194-0. .p FROST 2,226,602

' AUTOMATIC SETTING DEVICE FOR SHUTTERS AND DIAPHRAGMS OF PHOTOGRAPHICAPPARATUS Filed Jan. 18, 1938 In venfor Paul Frasf I "Ho/7 By HisAflomey Patented Dec. 31, 1940 PATENT OFFICE AUTOMATIC saTTmG nnvrca roasnUT- TEE S AND DIAPHRAGMS OF PHOTO- GRAPHIC APPARATUS Paul Frost,Munich-Neuharlaching, Germany, as-

signor, by mesne assignments, line a Film Corporation,

poration of Delaware to General Ani- New York, N. Y., a cor- ApplicationJanuary 18, 1938, Serial No. 185,507 In Germany January 18, 1937 4Claims.

of the invention will be apparent from the fol lowing detaileddescription.

ing, in which v Figure 1 is a circuit diagram of the new settingapparatus;

Figure 2 is a detail view of the pointer of the galvanometer acting as apawl;

Figure 3 shows the housing of the sector shutter in which a rectifierphotocell, a photocell diaphragm and a galvanometer are constructed, and

Figure 4-shows the setting mechanism constructed in the shutter housingwith a photocell resistance, photocell and galvanometer.

photographic shutter by a setting device controlled with the aid of acontact galvanometer, an auxiliary source of current and a relay. It hasalso been proposed to use the index of a photoelectric measuringapparatus as a diaphragm. Neither apparatus is adapted for constructionin a photographic camera because if an auxiliary current source andphotoelectric'relay are used the size and cost of the camera areincreased to an inconvenient extent, and if a rotating coil instrumentof which the index is formed as the diaphragm oi the objective is used,the index is so sensitive that even the least movement or vibration ofthe camera produces a movement of the diaphragm.

By this invention the problem of automatic setting of the shutter ordiaphragm is solved in a difierent way; the shutter or diaphragm isoperated by setting mechanism which also operates means for reducing thecurrent in the circuit of a photoelectric cell, and is automaticallystopped in its setting motion by theindex of a device responsive toelectric current (hereinafter referred to as a galvanometer) at aposition dependent on the position of the said index. The settingmechanism is preferably a delayed action mechanism operated by thetensioning spring of the shutter and .running under retardation. Thesetting mechanism, the photocell, the means for reducing the current andthe galvanometer can all be constructed in the shutter housing. Theindex of the galvanometer, which, owing to the gradual reduction or thephotoelectric 1-current, returns Reference is made to the accompanyingdrawsooner or later, according to the prevailing intensity of light, toits zero position, may be formed in such a manner that it can engage ina stop wheel of the setting mechanism without straining its bearings.

' In front oi the rectifier photocell l is a diaphragm :2 for-adjustingthe aperture of the cell. A variable resistance 3 can be adjustedto'suit the sensitivity of the photographic material, the aperture ofthe objective diaphragm, the effect of a fllter'or the like. A movingcoil galvanometer l is inxthe circuit of. the photocell i and has apointer 5 of which the free end' ia is hooked and extends into the pathof the stop of a stop wheel 6. The pointer has the iorm of a double.loop 5b and its free end 50 moves between fixed bars 1 'whichglpreventpressure being exerted on v the bearings 8 of the pointer when its endengages in the teeth of the stop wheel 8.

Figure 3 shows the shutter housing 9, in which 1 the magnet. In of thegalvanometer 4, the photo- It has been proposed to set the diaphragm ofa cell l and the photocell diaphragm 2 are arranged concentrically withthe opening 'II for the objective. Instead ofthe diaphragm 2 there maybe used a resistance (Figure 4) connected in the photocell circuit'inseries with the resistance 3. By the invention the diaphragm 2 or theresistance I2 is adjusted directly by the setting lever l3 of theshutter either by a flexible rider ll sliding on the winding 01 theresistance l2 and fixed to the lever l3 (see Figure 4) or by virtue ofthe diaphragm! being integral with the lever I3 (see Figure 3); Thelever I3 is, in known manner, under the tension of a strong spring l5which tensions the shutter and the setting mechanism It. The settingmechanism It consists in a train of gear wheels which run against aretarding action and (in the device of Figure 4) are driven by a pawl Ilcarried by the annular portion I30 of the lever i3 which pawl engages aratchet l8 during the tensioning oi! the shutter. 0n the pawl ll thereis a pin Ila, which slides on a cam surface I! when the mechanism is inmotion, strains the pawl ll, against the action of a spring 20, fromaccidental engagement with the mechanism It. On the axle of the wheel llthere is mounted a lever 21 which is connected with the toothed sector22 of the shutter speed controlling device 23. The usual spring 22anormally urges sector 22 to the left to its original starting position.The pointer 5, 5a of the galvanometerengages with the fastest. runningwheel of the setting mechanism It, namely thestop wheel i. At thedesired moment, the inner arm 24a of the reand during the settingmovement re-- lease lever 24 lifts the pawl I! from the ratchet teeth ofthe wheel l8 by means of the arm I'll). In an alternative constructionthe release lever 24 carries the bearing of the stop wheel 6 (see Figure3), so that by pressing down the lever 24 it turns, together with thestop wheel. 6, about the pivot 25, and the stop wheel is lifted fromengagement with the internal teeth Nb of the tensioning ring I3a. Inthis modification the setting mechanism i6 is driven by these internalteeth, rather than by the pawl construction of Figure 4.

The operation of the apparatus is as follows: The shutter is set undertension by moving the lever 13 from the position A to the position 13,whereby the diaphragm 2 is opened, or the resistance I2 is cut out ofthe photocell circuit since the diaphragm-6r the rider [4 is attached tothe lever 13. The photocell current generated by the light incident uponthe cell causes more or less deflection of the galvanometer pointeraccording to the brightness of the day. At the end of the movementoflever l3 the pawl l'I,-in the device of Figure-4, engages the ratchet l8of the mechanism l6, and drives the setting mechanism. As the settingmechanism ms, the tension lever l3 moves gradually from B to C and thelever 2| moves in the direction of the arrow D, and thereby adjusts thespeed of the shutter with the aid of the toothed sector 22. If the dayis bright, the relatively strong photocell current will produce a largedeflection of the galvanometer pointer, and the setting mechanism willaccordingly run for a relatively long time before the pointer 5a engagesin the stop wheel 6 of the setting mechanism so as to stop it. Theshutter speed corresponding with the brightness of the day is thusadjusted automatically by the appsratus described above. The shutter cannow be released at the desired moment by the release lever 24, whereuponthe setting mechanism locked by the pointer 5a is disengaged by thelifting of the pawl I I by means of the arm IIb.

Alternatively, it is possible to efiect this disengagement by pivotingthe stop wheel 6 as shown in Figure 3. In this modification the wheel 6is mounted on the release lever 24, which is pivoted at 25. The lever 24is heldby a locking device in the release position until the pin 2areleases the lever 24 at the end of a new tensioning movement, so thatthe stop wheel 6 can again engage in the teeth Nb of the ring, and canbe driven by said ring as the diaphragm closes, until the pointer 511looks the stop wheel.

I claim:

1. In a photographic shutter, a photo-electric cell, a diaphragm for'said cell, a shutter lever, means for tensioning the shutter, agalvanometer in electrical connection with said cell, a settingmechanism for controlling the diaphragm of said cell including a trainof interconnected gears, teeth carried by one of said gears, a ratchetfixed on a gear of said train, a pawl on said shutter lever adapted toengage said ratchet to operate said train of gears, means for adjustingthe speed of the shutter, means carried by a gear of said train foroperating said last named means and a pointer on said galvanometeradapted to engage the teeth of said gear to stop the motion of said geartrain.

2. In a photographic shutter, in combination with a controlling meansfor the exposure, an automatic setting device for regulating saidcontrolling means comprising a photo-electric cell, a diaphragm for saidcell, a setting mechanism for controlling said diaphragm and theexposure controlling means and including a toothed wheel, a galvanometerin electrical connection with said cell and a pointer carried by saidgalvanometer adapted to engage said toothed wheel for stopping saidsetting mechanism.

3. In a photographic shutter, in combination with a controlling meansfor the exposure, an automatic setting device for regulating saidcontrolling means comprising a photo-electric cell, a diaphragm for saidcell, a setting mechanism for controlling said diaphragm and theexposure controlling means including a toothed wheel, a galvanometer inelectrical connection with said cell, a pointer carried by saidgalvanometer adapted to engage said toothed wheel for stopping saidsetting mechanism, and a resistance for reducing the current produced bysaid photoelectric cell.

4. In a photographic shutter, in combination with a shutter housing anda controlling means for the exposure, an automatic'setting device forregulating the controlling means located in said housing andcomprising'a photo-electric cell, a diaphragm for said cell, a settingmechanism for controlling said diaphragm and the exposure controllingmeans and including a toothed wheel, a galvanometer in electricalconnection with said cell and a pointer carried by said galvanometeradapted to engage said toothed wheel for stopping said settingmechanism.

PAUL FROST.

